1. Field of the Invention
The present invention relates to a line facility for producing a structure, in which support-receipt plates are moved and driven in step for each working step place on a moving path located along a plurality of the working step places, so that a large-size structure including hull blocks, girder blocks of a bridge or the like is sequentially formed on the support-receipt plate.
2. Description of the Related Art
In recent years, construction of a large-size vessel or bridge is carried out by a block construction method, in which the vessel or the bridge is divided into a plurality of blocks.
A proposed line facility for producing a structure constituted of divided blocks is as shown in FIG. 1.
Namely, in the line facility for producing the structure, on a rail 11′ located on a floor surface along a plurality of working step places P′, support-receipt plates (i.e., skids 20′) are mounted to be movable with wheels interposed therebetween. Further, the line facility for producing the structure is provided with a driving mechanism 30′ for moving and driving the skids 20′. The skids 20′ are moved and driven in step for each working step place P′ by the driving mechanism, and then structure blocks are sequentially formed on the skids 20′. The skids 20′ are located in plural so as to correspond to the respective working step places P′. The skids 20′, which reach the final step of the production line (in which the structure blocks are completed), and from which the structure blocks are discharged, are carried to a first step place of the production line by a ceiling crane or the like, and are sequentially reused.
The driving mechanism 30′ is constituted of a driving device such as a motor. A chain 31′ driven around an orbit along the rail 11′ by the driving mechanism 30′ and the skids 20′ to be moved thereon are coupled to each other. The driving mechanism 30′ is driven to move the chain 31′ around the orbit. There is another driving mechanism 30′ constituted, in which a wire rope having a tip coupled to the skid 20′ to be moved is wound by a winding device, and then this driving mechanism is driven to pull the skid 20′.
However, in the line facility for producing the structure, which is constituted as described above, there has been a problems below. A total weight of the skids 20′ and the structure blocks supported by the skids 20′ is extremely enlarged. Thus, as shown by thick arrows in the drawing, the support-receipt plates must be moved sequentially one by one. Therefore, it takes time for the moving working thereof. Of course, during the moving working, the construction working cannot help but be interrupted, such that the production efficiency is lowered. Moreover, in order to move and drive the plurality of support-receipt plates simultaneously, the output and strength of the driving mechanism must be extremely enlarged, so that the proposed line facility is not a practical line facility for producing the structure.
For the purpose of improving the space efficiency in the plant, a line constitution (see FIG. 2) has been adopted in many cases, in which a production line makes a U-turn in a halfway thereof. However, with this line constitution, the driving mechanism becomes complicated, thereby enlarging the facility. Therefore, there have been problems that the facility expenses are increased, and that the work efficiency is low.
As shown in FIG. 2, in the line constitution for producing the structure, an approach path 10A′ and a back path 10C′ are located parallel to each other. Moreover, a terminated working step place of the approach path 10A′ and a starting working step place of the back path 10C′ are connected by a connection path 10B′. The skids 20′ moved and driven in step for each working step place P′ on the approach path 10A′ reach the terminated working step place of the approach path 10A′. Thereafter, the skids 20′ are moved and driven in to the starting working step place of the back path 10C′ through the connection path 10B′. Subsequently, the skids 20′ are moved and driven in step for each working step place P′ in the back path 10C′, and then reach the terminated working step place of the line.
In the line constituted as described above, a driving mechanism is required for each of the approach path 10A′, the connection path 10B′ and the back path 10C′. Further, it is necessary to constitute the line so that each driving means (a chain, a wire rope or the like) cannot interfere with the others. Thus, the line constitution becomes extremely complicated and large in scale. In addition, when the direction of the skids 20′ is changed from the approach path 10A′ to the connection path 10B′ and from the connection path 10B′ to the back path 10C′, it is necessary to change the direction of the skids 20′ by a method for floating the wheels from the rail 11′, in which the skids 20′ are lifted by a jack or the like. The constitution for this direction change becomes complicated and large in scale. Moreover, the working itself of changing the direction of the skids 20′ is cumbersome, and time is required therefore.